11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Janesville | 1 | 66,390 | 65,670 | 0.22% | 1,929 | 34.42 | City |
| Beloit | 2 | 36,118 | 36,677 | -0.31% | 2,083 | 17.34 | City |
| Edgerton | 3 | 6,023 | 5,943 | 0.27% | 1,448 | 4.16 | City |
| Evansville | 4 | 5,877 | 5,741 | 0.46% | 1,804 | 3.26 | City |
| Milton | 5 | 5,613 | 5,725 | -0.39% | 1,208 | 4.65 | City |
| Clinton | 6 | 2,235 | 2,215 | 0.18% | 1,561 | 1.43 | Village |
| Orfordville | 7 | 1,490 | 1,467 | 0.34% | 1,255 | 1.19 | Village |
| Footville | 8 | 871 | 773 | 2.35% | 772 | 1.13 | Village |
| Shopiere | 9 | 241 | 200 | 7.11% | 1,111 | 0.22 | CDP |
| Allens Grove | 10 | 193 | 161 | 7.22% | 337 | 0.57 | CDP |
| Hanover | 11 | 144 | 119 | -1.37% | 247 | 0.58 | CDP |
Janesville is the largest city in Rock County, with a population of 66,390.
Hanover is the smallest city in Rock County.
There are 11 cities in Rock County, Wisconsin.